1. Filed of the Invention
The present invention relates to GM.sub.3 analogous compounds and a process for preparing the compounds. More particularly, the present invention relates to GM.sub.3 analogous compounds exhibiting higher stability and usable as a cancer antigen, and intermediates thereof.
2. Description of the Related Art
Glycolipids found in mammal cells are glycosides between ceramides, which are sphingosines (long chain amino alcohols) to which aliphatic acids have been attached through an amide linkage, and one or more sugars such as glucose, galactose, N-acetyl glucosamine, N-acetyl galacotosamine, fucose, sialic acid, etc. Among these glycosides, those containing sialic acid are called gangliosides.
Gangliosides exsit mainly in the outer leaflet of the bilayer of the mammal cell membrane. Recent studies show that gangliosides play important roles in reception and recognition of, and response to, information in cells, receptor mechanism, differentiation, cell propagation, malignant cell transformation, cell behavior, etc.
It has been known that the ganglioside GM.sub.3, one of the above-mentioned gangliosides, closely relates to differentiation of intestinal tissue and contact inhibition of cell growth. It has been also known that the growth of fibroblast of baby hamsters in the presence of fibroblast factor is specifically inhibited by the presence of ganglioside GM.sub.3 added from the outside. Further, ganglioside GM.sub.3 has been detected in the natural melanoma cells as a tumer associated antigen.
Recently, by using the gangliosides, preparation of a monoclonal antibody recognizeing the oligosuccharides and pharmaceutical preparations having the biological activity thereof have been developed (see Japanese Patent Disclosure Nos. 63-301796 and 1-132374 (JP-A-301796/1988 and JP-A-132374/1989).
At the preparation of a monoclonal antibody by using ganglioside 9-O-acetyl GM.sub.3 as the antigen, the low chemical stabiltiy of ganglioside 9-O-acetyl GM.sub.3 is a problem. That is, since the chemical stabiltiy of ganglioside 9-O-acetyl GM.sub.3 is low, it was hard to prepare a monoclonal antibody to ganglioside 9-O-acetyl GM.sub.3.